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Abstract

A significant reduction in summer monsoon rainfall has been observed in northern central India during the second half of the twentieth century, threatening water security and causing widespread socio-economic impacts. Here, using various observational data sets, we show that monsoon rainfall has increased in India at 1.34 mm d−1 decade−1 since 2002. This apparent revival of summer monsoon precipitation is closely associated with a favourable land–ocean temperature gradient, driven by a strong warming signature over the Indian subcontinent and slower rates of warming over the Indian Ocean. The continental Indian warming is attributed to a reduction of low cloud due to decreased ocean evaporation in the Arabian Sea, and thus decreased moisture transport to India. Global climate models fail to capture the observed rainfall revival and corresponding trends of the land–ocean temperature gradient, with implications for future projections of the Indian monsoon.

Schneider, U.et al.GPCC’s new land surface precipitation climatology based on quality-controlled in situ data and its role in quantifying the global water cycle. Theor. Appl. Climatol.115, 15–40 (2014).

Acknowledgements

This study was supported by the US National Science Foundation (AGS-1339264), US DOE (DE-FG02-94ER61937), and the National Research Foundation (NRF) of Singapore to the Center for Environmental Sensing and Modeling (CENSAM) of the Singapore-MIT Alliance for Research and Technology (SMART) centre. We acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modelling groups for producing and making their model output available. For CMIP the US Department of Energy’s Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. We truly appreciate the efforts of various responsible groups for making their observational or reanalysis data publicly available. We also thank D. Rothenberg for providing scripts to download the CMIP5 data and his valuable comments on this work.